A lot of people feel that satan and devil can be used interchangeably because they mean the same thing. A lot of people agree with this. The satan and the devil are entities that will try to tempt people to do bad things as compared to doing good things. They will try to seduce humans into doing some sins that will make them bad in the eyes of their God.
The only difference between the two is that Satan or Lucifer is considered to be the name of God’s favorite angel before he fell down from heaven. There are some people who say that there is more than one devil available and they are meant to tempt people into doing things that are considered to be evil.